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<head><meta charset="utf-8"><title>design meeting: vtables etc lang-team#55 · t-lang · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/index.html">t-lang</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html">design meeting: vtables etc lang-team#55</a></h3>

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<a name="214629102"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214629102" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214629102">(Oct 26 2020 at 20:31)</a>:</h4>
<p>Hey so i'm going to start pulling together some notes for <a href="https://github.com/rust-lang/lang-team/issues/55">lang-team#55</a></p>



<a name="214629127"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214629127" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214629127">(Oct 26 2020 at 20:31)</a>:</h4>
<p>I started by reviewing the Backlog Bonanza note</p>



<a name="214629184"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214629184" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214629184">(Oct 26 2020 at 20:32)</a>:</h4>
<p>where I see we cited <a href="https://github.com/rust-lang/rfcs/pull/2967">https://github.com/rust-lang/rfcs/pull/2967</a> as related work (cc @oli)</p>



<a name="214629193"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214629193" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214629193">(Oct 26 2020 at 20:32)</a>:</h4>
<p>er, cc <span class="user-mention" data-user-id="124288">@oli</span></p>



<a name="214629327"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214629327" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214629327">(Oct 26 2020 at 20:33)</a>:</h4>
<p>I think the summary we produced in the meeting of:</p>
<ul>
<li>Review what <a href="https://github.com/rust-lang/rfcs/issues/2580">rfc#2580</a> is proposing (some limited APIs that aim to maintain forward compat)</li>
<li>Review some of the things they aim to be forward compat <em>with</em> </li>
</ul>
<p>is probably correct.</p>



<a name="214629373"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214629373" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214629373">(Oct 26 2020 at 20:33)</a>:</h4>
<p><span class="user-mention" data-user-id="124288">@oli</span> would you like to attend the meeting? the plan is for it to take place at <time datetime="2020-11-04T18:00:00Z">2020-11-04T13:00:00-05:00</time></p>



<a name="214630009"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214630009" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214630009">(Oct 26 2020 at 20:39)</a>:</h4>
<p>Thanks for the ping. I'll def participate</p>



<a name="214630578"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214630578" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214630578">(Oct 26 2020 at 20:44)</a>:</h4>
<p><span class="user-mention" data-user-id="124288">@oli</span> want me to add you to the calendar invite?</p>



<a name="214630606"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214630606" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214630606">(Oct 26 2020 at 20:44)</a>:</h4>
<p>I am writing up a <a href="https://hackmd.io/1Fq9TcAQRWa4_weWTe9adA">hackmd with notes</a> and would love feedback</p>



<a name="214631760"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214631760" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214631760">(Oct 26 2020 at 20:54)</a>:</h4>
<p>Yes please. I'll review the hackmd tomorrow,</p>



<a name="214693693"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214693693" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214693693">(Oct 27 2020 at 12:45)</a>:</h4>
<p>I reviewed the doc, changed some minor things and left some notes for the meeting</p>



<a name="214719981"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214719981" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214719981">(Oct 27 2020 at 15:52)</a>:</h4>
<p>I think the major thing missing from the doc <span class="user-mention" data-user-id="116009">@nikomatsakis</span> is sort of the "agenda" of the meeting in some sense -- maybe something like:</p>
<ul>
<li>Summarize current state of the problem and solution space</li>
<li>Try to determine if we'd be comfortable with proposed solutions in RFC 2580 on nightly?</li>
</ul>
<p>I'm not quite sure if that's what we're hoping for from the meeting :)</p>



<a name="214730991"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214730991" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214730991">(Oct 27 2020 at 17:04)</a>:</h4>
<p><span class="user-mention" data-user-id="116122">@simulacrum</span> yes, that was roughly my plan. I had expected to talk out some of the extensions too. I see <span class="user-mention" data-user-id="124288">@oli</span> added some notes and they are a few comments. I'm thinking about whether there are any key questions to pre-identify as worth spending time on</p>



<a name="214731427"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214731427" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214731427">(Oct 27 2020 at 17:06)</a>:</h4>
<p>I think the main question is what the minimal useful API is that we can expose that still allows for all extensions we would like, so maybe we need to list all the possible (well, asked-for at least) extensions?</p>



<a name="214731492"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214731492" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> oli <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214731492">(Oct 27 2020 at 17:07)</a>:</h4>
<p>this partially exists in the doc already, but I'll build a summary list of all the features I can find</p>



<a name="214865757"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214865757" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214865757">(Oct 28 2020 at 16:54)</a>:</h4>
<p><span class="user-mention" data-user-id="124288">@oli</span> yeah that'd be helpful</p>



<a name="214865805"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214865805" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214865805">(Oct 28 2020 at 16:54)</a>:</h4>
<p>I did go through the "custom dst" RFC in "mild detail" in terms of vetting what interactions there would be</p>



<a name="214865815"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/214865815" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#214865815">(Oct 28 2020 at 16:55)</a>:</h4>
<p>but I imagine a more detailed look would be good</p>



<a name="215615631"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215615631" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215615631">(Nov 04 2020 at 17:35)</a>:</h4>
<p>Hey <span class="user-group-mention" data-user-group-id="1977">@T-lang</span> reminder that we have a design meeting in ~25 minutes.</p>
<p>Here is the meeting preparation document <a href="https://hackmd.io/1Fq9TcAQRWa4_weWTe9adA">https://hackmd.io/1Fq9TcAQRWa4_weWTe9adA</a></p>



<a name="215615772"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215615772" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215615772">(Nov 04 2020 at 17:36)</a>:</h4>
<p><span class="user-mention" data-user-id="124288">@oli</span> do you happen to be around now?</p>



<a name="215618617"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215618617" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215618617">(Nov 04 2020 at 17:59)</a>:</h4>
<p>reminder to <span class="user-mention" data-user-id="219747">@Simon Sapin</span> and <span class="user-mention" data-user-id="124288">@oli</span></p>



<a name="215618840"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215618840" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215618840">(Nov 04 2020 at 18:00)</a>:</h4>
<p><span class="user-group-mention" data-user-group-id="1977">@T-lang</span> design meeting starting soon</p>



<a name="215619097"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215619097" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Simon Sapin <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215619097">(Nov 04 2020 at 18:02)</a>:</h4>
<p>(Zulip is being very slow here for some reason…)</p>



<a name="215619123"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215619123" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Simon Sapin <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215619123">(Nov 04 2020 at 18:02)</a>:</h4>
<p>Is this a video call?</p>



<a name="215619272"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215619272" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215619272">(Nov 04 2020 at 18:03)</a>:</h4>
<p><span class="user-mention" data-user-id="219747">@Simon Sapin</span> whoops :) yes it is</p>



<a name="215619279"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215619279" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215619279">(Nov 04 2020 at 18:03)</a>:</h4>
<p>I'll ping you the URL</p>



<a name="215619367"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215619367" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nikomatsakis <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215619367">(Nov 04 2020 at 18:04)</a>:</h4>
<p>(it's in the calendar invite I added you to)</p>



<a name="215626897"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/213817-t-lang/topic/design%20meeting%3A%20vtables%20etc%20lang-team%2355/near/215626897" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Josh Triplett <a href="https://rust-lang.github.io/zulip_archive/stream/213817-t-lang/topic/design.20meeting.3A.20vtables.20etc.20lang-team.2355.html#215626897">(Nov 04 2020 at 19:04)</a>:</h4>
<p>Based on the discussion in the meeting, I <em>would</em> like to see the <code>'static</code> bound dropped on <code>Metadata</code> before we merge, in favor of <span class="user-mention" data-user-id="116009">@nikomatsakis</span>'s argument that we can infer the lifetime we need when we need it.</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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